This is the northernmost constituency on mainland Britain and covers a vast but sparsely populated area - the electorate is about 13,000 short of the Scottish average.

Caithness forms the northern tip of this seat, and is made up of farming and fishing communities around the two main towns of Thurso and Wick.

Dounreay nuclear power station is also located here, and tourism is helped by the presence of John O'Groats.

The mountains and moorland of Sutherland, to the west and south, are bleaker in appearance, but also attract considerable numbers of holidaymakers captivated by countryside that, if rugged, is undoubtedly of some beauty.

The Easter Ross element of the seat is much the smallest in terms of area but is far more densely populated, including the fairly large town of Invergordon, home to many workers in oil-related industries and the remnants of the smelter and Nigg yard workforces.

The current MP Bob MacLennan has represented three different parties since his election in 1966, in turn Labour, the SDP and the Liberal Democrats, but has decided to step down at this election.